The invention relates to the field of evacuating gases from chambers to produce reduced pressures therein, and in particular to improvements in the operation of gas turbines, jet engines and rockets, as well as vacuum pumps and gas compressors.
In order to reduce the pressure in a chamber, it is well known to use a fan, compressor or other type of gas movement device to blow the gas in the chamber outwardly. The efficiency of such a device lasts only so long as there is gas in the chamber to be evacuated, since the gas assists in turning the fan blades, and reduces the amount of electrical power which must be used to operate the fan. When the pressure in the chamber has been reduced, there is less gas being moved to turn the fan blades, so more electrical power must be applied to the fan to move the blades. The reduction in efficiency at reduced pressures is considerable, and requires the use of a fan sized to be effective at reduced pressure.
Applicant has experienced the difficulties resulting from evacuating a chamber as the pressure is reduced in conjunction with operation of the power generation system disclosed in U.S. Pat. No. 5,444,981, incorporated herein by reference. In the closed system disclosed in that patent, a light, non-condensable gas, typically helium, is added to a working fluid, typically water, in a boiler. The working fluid is vaporized in the boiler, and the mixture of light gas and vaporized working fluid is used to operate a turbine to generate electric power. The light gas and working fluid mixture is then passed to a condenser to separate the working fluid from the light non-condensable gas, and the gas and working fluid are separately returned to the boiler.
As part of the cycle disclosed in that patent, a portion of the light gas may be returned to the boiler by way of aspiration by the working fluid or may be returned separately. Additionally, a compressor may be used to return the light gas to the boiler at high pressure.
In seeking to improve the process disclosed in the patent, applicant has used a fan to evacuate the light gas from the condenser, and pass it on to a compressor. However, applicant has noted the decrease in efficiency of the fan as pressure is reduced in the condenser, and a larger, more powerful fan must be used to maintain proper flow of light gas to the compressor.
Applicant's U.S. application No. 08/829,940 filed Apr. 1, 1997, now U.S. Pat. No. 5,810,564 proposes a solution to the problem of evacuating light gases with an apparatus comprising a housing having a lower, downwardly facing wall and an upper, upwardly facing wall, an inlet disposed within the lower wall and comprising a first gas flow director of truncated conical shape having a larger open end facing downwardly and a smaller open end facing upwardly, in flow communication with the housing. A plurality of stationary vanes is disposed at the smaller open end of the first gas flow director, for imparting a vortex flow to gas flowing therethrough.
An outlet is disposed within the upper wall of the housing comprising a second gas flow director of truncated conical shape and having a larger end facing downwardly and disposed within the housing and a smaller open end facing upwardly, external to the housing, the second gas flow director further comprising a circumferential surface portion disposed within the housing. The surface portion comprises outer and inner surfaces, and a means for closing the larger end of said second gas flow director, to prevent flow of gas therethrough. A plurality of slits is disposed longitudinally in this surface portion of the second gas flow director, each slit comprising a guide flap disposed on the outer surface and a guide flap disposed on the inner surface for guiding gas flow through the slit.
A heating device is disposed within the second gas flow director and a deflector is disposed within the housing adjacent the means for closing to direct gas flow away from the means for closing and towards the outer surface of the circumferential surface portion.
In the method for using this apparatus, the gas in the outlet is heated by the heating device to a temperature at least about 16.degree. C. above ambient to increase gas flow through the device.